There are many manufactures producing +30% and +50% replacement bulbs such as Osram/Sylvania, Philips, Hella ... I bought the +30% Hella H4 bulbs to use in Lexus LS400 about three years ago, it burnt in less than 1 year. I replaced it with Philips Vision Plus which is the +50% type, it generates more light than the +30% type and its light is whiter too, so far it still working.
You should get the +50% bulb for about $1 more each. You will see the road at night much better than standard bulb.